functional health literacy, medication-taking self-efficacy and adherence to antiretroviral therapy

ORIGINAL RESEARCH

Functional health literacy, medication-taking self-efficacy and

adherence to antiretroviral therapy

Alison M. Colbert, Susan M. Sereika & Judith A. Erlen

Accepted for publication 10 March 2012

Correspondence to A.M. Colbert:

e-mail: [email protected]

Alison M. Colbert PhD RN

Assistant Professor

School of Nursing, Duquesne University,

Pittsburgh, Pennsylvania, USA

Susan M. Sereika PhD

Assistant Professor

School of Nursing, University of Pittsburgh,

Pennsylvania, USA

Judith A. Erlen PhD RN

Professor and Department Chair, Health and

Community Systems

School of Nursing, University of Pittsburgh,

Pennsylvania, USA

COLBERT A.M., SEREIKA S.M. & ERLEN J.A. (2012)COLBERT A.M. , SEREIKA S.M. & ERLEN J.A. (2012) Functional health literacy,

medication-taking self-efficacy and adherence to antiretroviral therapy. Journal of

Advanced Nursing 00(0), 000–000. doi: 10.1111/j.1365-2648.2012.06007.x

AbstractAims. To report a study of the relationship between functional health literacy and

medication adherence, as mediated by medication-taking self-efficacy, while con-

trolling for the effect of key demographic variables (such as race, income and level of

education).

Background. Medication adherence is critical to successful HIV/AIDS self-man-

agement. Despite simplified regimens and the availability of tools to assist with

medication-taking, adherence remains a challenge for many people living with HIV/

AIDS.

Design. Cross-sectional, secondary analysis.

Methods. Data for this study of 302 adults living with HIV/AIDS who were taking

antiretroviral medications were collected from January 2004–December 2007.

Medication adherence was measured using electronic event monitors. Bivariate

analyses and stepwise regression were conducted to examine the associations among

functional health literacy, medication-taking self-efficacy and HIV medication

adherence.

Results. Overall, functional health literacy was much higher than expected; how-

ever, adherence in this sample was sub-optimal. Higher medication-taking self-

efficacy was associated with higher medication adherence; however, functional

health literacy was not significantly related to either medication adherence or self-

efficacy beliefs. Hence, medication-taking self-efficacy did not mediate the rela-

tionship between functional health literacy and medication adherence.

Conclusions. Medication adherence continues to be an issue for people living with

HIV/AIDS. Additional research is needed to understand the disparate findings

related to functional health literacy and medication adherence in this and other

studies examining this association.

Keywords: health literacy, HIV, medication adherence, nurses, nursing, self-efficacy

� 2012 Blackwell Publishing Ltd 1

J A N JOURNAL OF ADVANCED NURSING

Introduction

Successful self-management of HIV requires substantial effort

on the part of the individual because of the need for

consistent and effective medication taking behaviours.

Research has shown that viral suppression may require

nearly 100% adherence, but maintaining rates greater than

95% translates into less than one missed dose per week for a

patient on a twice-a-day pill regimen (Deeks et al. 1999,

Paterson et al. 2000). Effective management of HIV/AIDS is

a global issue, as there are approximately 33 million people

living with HIV/AIDS in the world today and 5 million are

currently receiving an HIV medication (Joint United Nations

Programme on HIV/AIDS 2010). Nurses are in an ideal

position to help patients to better manage their medication

regimen and this nursing role requires a solid understanding

of the various aspects of adherence. Functional health literacy

may be one of the many factors influencing the health

management behaviours of people living with HIV.

Background

Medication adherence is a critical issue in the management of

HIV/AIDS because poor rates of adherence can lead to

unsuccessful viral suppression, resistance to medication,

opportunistic infections, overall poor health, decreased

quality of life and potentially death (Bangsberg et al. 2001,

McNabb et al. 2003, Carballo et al. 2004). Therefore,

persons with HIV/AIDS who have inadequate functional

health literacy are even more vulnerable in accessing health

services and are at greater risk for poor health outcomes.

Even when they access health services and have discussions

with nurses about their medications, the person with lower

functional health literacy may not know what questions to

ask or may not fully comprehend what the nurses are

explaining to them. Researchers estimate the proportion of

people living with HIV/AIDS who demonstrate lower or

marginal functional health literacy level to be around 18–

20% (Kalichman & Rompa 2000, Golin et al. 2002, Drai-

noni et al. 2008, Kalichman et al. 2008).

Several published studies have directly examined the

association between functional health literacy and medica-

tion adherence in people living with HIV; however, the

results are inconsistent. Several authors showed that lower

functional health literacy is related to poorer adherence

(Kalichman et al. 2007, Osborn et al. 2007, Kalichman et al.

2008, Osborn et al. 2010). Conversely, others have found

that lower functional health literacy was not associated with

lower medication adherence (Golin et al. 2002, Wolf et al.

2004, Paasche-Orlow et al. 2006, Wolf et al. 2007, Murphy

et al. 2010). Among those, Paasche-Orlow et al. (2006)

found that low functional health literacy was not associated

with lower odds of adherence or viral suppression in a

population of 235 individuals who were HIV-positive and

had a history of alcohol problems. In fact, the authors

reported a non-significant trend that lower functional health

literacy might be associated with better adherence and

virological suppression.

The disparate findings may be attributable to issues of

measurement relative to the variables of interest. The

measurement of adherence is a complicated and controversial

issue. Individuals with lower functional health literacy may

have difficulty understanding what information is necessary

to report when asked about their adherence levels. In turn,

this may have an effect on studies investigating adherence. In

a qualitative study of 25 HIV-positive patients (75% with

lower functional health literacy as assessed by the Rapid

Estimate of Adult Literacy in Medicine), Wolf et al. (2005)

examined the association of health literacy with the partic-

ipants’ responses to HIV medication-adherence question-

naires. The authors’ analysis revealed several themes related

to format, administration and visual aids. The majority of

respondents thought that adherence measured as recall over

3 days was not accurate. In addition, most believed they

would require one-on-one assistance to complete a self-report

measure accurately (Wolf et al. 2005). These findings raise

issues about the validity of self-report as a measure of

adherence in people with lower functional health literacy.

Although all methods of measurement have their unique

problems, electronic event monitoring (EEM), a method for

indirectly monitoring mediation adherence, is believed to

offer more information over time than biological assays

(Turner 2002) and may be a more appropriate choice when

considering adherence in the context of health literacy. EEM

consists of a medication cap containing a micro-electronic

circuit that fits on a standard medication bottle and records

the time and date each time the bottle cap is opened.

However, most studies exploring adherence and health

literacy used self-report as the measure of adherence; those

that did not used pharmacy refills or pill counts (Graham

et al. 2007, Kalichman et al. 2007, 2008). Golin et al. (2002)

used a composite score that comprised of electronic moni-

toring, pill counts and self-report.

Measures of health literacy used among the published

studies also vary with the most commonly used measure

being the short version of the Test of Functional Health

Literacy in Adults (S-TOFHLA) and the Rapid Estimate of

Adult Literacy in Medicine (REALM). The S-TOFHLA,

described in greater detail below, measures the ability to

understand prose and to read and understand numerical

A.M. Colbert et al.

2 � 2012 Blackwell Publishing Ltd

information related to health management (Baker et al.

1999). The REALM is a 66-word recognition and pronun-

ciation test (Davis et al. 1993). In addition, the cut-off points

distinguishing higher and lower health literacy scores varied

across studies.

When considering the issue of HIV medication adherence,

researchers have explored how confidence in one’s ability to

take medication (self-efficacy) may be related to outcomes.

Results from several studies have supported the relationship

between higher self-efficacy and better HIV medication

adherence (Buchmann 1997, Catz et al. 2000, Simoni et al.

2002, Johnson et al. 2003, Cha et al. 2008) providing a

rationale for continued inquiry into the relationship between

self-efficacy and adherence and how other factors may be

influenced by self-efficacy. This association is supported

across diverse HIV-positive populations. Researchers found

that self-efficacy mediated the relationship between health

literacy and HIV medication adherence, as measured by self-

report (Wolf et al. 2007). An individual’s ability to read and

understand health directions may indeed be influenced by

their confidence in their abilities to take their medications

under different and changing circumstances.

Nurses working with people living with HIV/AIDS are in

an important position to assist with medication adherence

and to facilitate effective self-management strategies related

to medication taking. Orem’s self-care deficit nursing theory

posits that the nurse must comprehensively assess a patient

to identify key deficits related to self-care and that care

should then be provided according to the degree of the

deficit. Functional health literacy, medication-taking self-

efficacy and medication adherence are all potential areas for

deficits and research into how these issues are related may

give additional insight into how best to intervene (Orem

2001).

Bandura’s Social Cognitive Theory guided the selection of

variables of interest for this study; this framework focuses

heavily on the role of self-efficacy in behaviour. Bandura

(1997) asserts that self-efficacy is the self-assurance with

which individuals approach tasks to accomplish a specific

behaviour; self-efficacy determines whether or not people

make good use of their capabilities and can ultimately be

successful. Functional health literacy may play an important

role in an individual’s development of self-assurance in the

context of health.

Using the published literature and Bandura’s theory, we

hypothesized that (1) functional health literacy has a direct,

positive effect on medication-taking self-efficacy; and (2)

functional health literacy has an indirect, positive effect on

HIV medication adherence through medication-taking self-

efficacy.

The study

Aims

The article is a report of a study of the relationship between

functional health literacy and medication adherence, as

mediated by medication-taking self-efficacy, while control-

ling for the effects of key demographic variables (such as race,

income and level of education).

Design

This secondary analysis was a correlational study that used

de-identified baseline data obtained from the parent study,

‘Improving Adherence to Antiretroviral Therapy’ (2R01

NR04749, J. A. Erlen, PI), to address the aims of the study

and to test the hypotheses. The parent study’s project director

served as an honest broker, collecting and collating all

relevant data and replacing any identifiers with a code,

thereby making it impossible for the study investigators to

identify the participants. This process assured subject ano-

nymity. Data were collected from January 2004–December

2007. The parent study is a randomized clinical trial

comparing the efficacy of two nurse-delivered telephone

interventions (structured and individualized) on HIV medica-

tion adherence (Wickersham et al. 2011). The interventions,

focused on habit formation and problem solving, were based

on social cognitive and self-efficacy theory (Bandura 1997).

Sample/participants

Participants for the parent study were recruited from western

Pennsylvania and eastern Ohio via clinics and community

organizations serving people living with HIV/AIDS. All

participants from the parent study who completed the

functional health literacy assessment were included in this

analysis. To be eligible for the parent study, participants had

to be 18 years of age or older, able to speak and understand

English, free from HIV-related dementia as evidenced by

assessment using an HIV dementia tool (Power et al. 1995),

prescribed HIV medications, self administering the prescribed

HIV-antiretroviral medication and not living with a current

participant in the study.

A total of 354 participants were enrolled in the parent

study; of these 18 (5Æ1%) were excluded from this secondary

analysis because the functional health literacy assessment was

not completed. An additional three participants (0Æ8%) were

excluded due to a lack of electronic adherence data; all three

of these participants were classified as having adequate

functional health literacy. Finally, the secondary analysis

JAN: ORIGINAL RESEARCH Health literacy and HIV adherence


included only those participants who self-reported as White

or African American, due to the very small number of people

not included in one of those two groups, their heterogeneity

(n = 31, 9Æ3% of those with adequate data, from eight

different ethnic groups) and the study aim of examining race

as a potential confounding variable. Therefore, the final

sample for this study included 302 participants.

Data collection

All data were collected as part of the parent study. At the first

visit, participants were screened for inclusion and enrolled if

eligible. They were instructed in the use of the medication

diary and the electronic event monitor and asked to return

home and use the monitor for approximately 1 month with

one antiretroviral medication, randomly selected by project

staff. One month later participants were mailed a booklet of

questionnaires, allowing them to complete the self-adminis-

tered measures at home. The participants then returned for

the baseline data collection, at which time the data from the

electronic event monitors were downloaded, the functional

health literacy tool was administered and the remaining

questionnaires that required face-to-face format or that they

be timed were completed. These data were collected prior to

randomization in the parent study. The specific data used in

this study were obtained during the baseline data collection

session.

Functional health literacy was measured using the Short

Test for Functional Health Literacy (Baker et al. 1999). The

S-TOFHLA is a shorter version of the standard TOFHLA

which uses materials a patient may encounter in the context

of healthcare, such as patient instructions for surgery and a

prescription bottle. Functional health literacy was dichoto-

mized as inadequate/marginal (£ 75) or adequate (>75). The

S-TOFHLA demonstrated high internal consistency reliabil-

ity, with a Cronbach’s alpha of 0Æ953.

Adherence was objectively assessed using EEM, augmented

by daily diary self-report. EEM consists of a medication cap

containing a micro-electronic circuit that fits on a standard

medication bottle and records the time and date each time the

cap is opened. Participants were also asked to keep a daily

diary to track pocket dosing and refills of the medication

bottle. In these instances, the EEM data were augmented by

data from the medication-taking diary before summarizing

data to adherence indices.

For analysis, adherence was reported as both a continuous

variable (percentage of days with the correct intake or

percentage of number of prescribed administrations taken)

and a categorical variable based on the continuous variable

(<85% adherence, ‡ 85% adherence). This cut-off was

chosen because it reflects a moderate to high level of

adherence. Although the traditional cut-off point in HIV is

often 95–100%, the lower threshold for ‘higher’ adherence

may be more consistent with Bangsberg’s (2006) research

demonstrating effectiveness of medications at lower levels of

adherence. For the regression models, percentage of days

with correct intake was used as the dependent variable.

Self-efficacy was conceptualized as medication-taking self-

efficacy beliefs, or one’s belief in his/her ability to plan and

perform a desired behaviour. Self-efficacy was measured

using the Self-Efficacy Beliefs subscale of the HIV Self-

Efficacy Scale for Medication Taking (Erlen et al. 2010). The

content relates specifically to antiretroviral medication taking

and measures the level, generality and strength of medication-

taking self-efficacy. The total score for the self-efficacy beliefs

subscale ranges from 17–170. The subscale demonstrated

good internal consistency reliability with a Cronbach’s alpha

of 0Æ95.

Two investigator-developed tools, the Health Survey and

Medical Record Review were used to collect HIV-health

history information. To provide the most accurate data

possible, we first used available medical records to obtain

CD4 counts and detectable/undetectable viral load data.

When medical records were unavailable, we used self-report

as an additional data source. The Center for Research in

Chronic Disorders (CRCD) Socio-demographic Question-

naire was used to collected socio-demographic information.

Ethical considerations

Institutional Review Board (IRB) approval was obtained for

this secondary data analysis; the parent study had separate

IRB approval. In the parent study informed consent was

obtained from all participants prior to screening or the

collection of any baseline data.

Data analysis

Analysis was performed using SPSSSPSS (version 16.0; SPSS Inc.,

Chicago, IL, USA) and SASSAS (version 9.2; SAS Institute Inc.,

Cary, NC, USA). Measures of central tendency (means,

medians) and dispersion (standard deviations, ranges) were

used to summarize the continuous-type participant descrip-

tors, medication adherence and self-efficacy; frequency

counts and percentages were used to summarize categorical

descriptors. Bivariate analyses (t-tests, Mann–Whitney

U-test, Pearson correlation, Spearman correlation and chi-

square tests of independence, as appropriate) were conducted

to examine the unadjusted associations between dichotomized

functional health literacy and selected socio-demographic

A.M. Colbert et al.


factors (as listed in Table 1) and HIV-health history infor-

mation (viral load, CD4 and number of medications) and

then the associations of those variables to medication

adherence.

To examine the relationship between functional health

literacy and medication adherence, stepwise multiple regres-

sion was performed treating medication adherence as the

outcome variable; included in the model were all variables

that met the screening criteria (P < 0Æ20) when examined

bivariately with adherence. The resultant models were

evaluated and modified to include only important correla-

tions and to identify the most parsimonious model. Signifi-

cance levels were set a priori at 0Æ05, except where indicated.

Due to the relatively small number of people with low health

literacy in this sample, we used bootstrapping to estimate

regression coefficient and confidence interval. A bootstrap

sample of 302 participants was generated by randomly

sampling with replacement from the original ‘real’ sample.

Since this new sample is drawn from the original sample via

sampling with replacement, the resulting bootstrap sample

would not be identical to the original sample. A multiple

regression was estimated on a bootstrap sample. Regression

coefficients were recorded. These steps were repeated 1000

times (i.e. 1000 bootstrap replication). An empirical sampling

distribution of a regression coefficient was estimated using

the results from the 1000 bootstrap replications. A 95%

confidence interval (CI) was computed for each regression

coefficient by computing the 2Æ5 and 97Æ5 percentile scores.

Table 1 Socio-demographic and health history variables of interest for the total sample and by functional health literacy (FHL) (inadequate/

marginal, £75; adequate, >75).

Variable

Sample

(N = 302)

Inadequate/

Marginal,

£ 75 (n = 30)

Adequate,

>75 (n = 272)

Difference between

FHL categories

n % n % n % v2 P value

Gender

Male 213 70Æ5 19 63Æ3 194 71Æ3 0Æ83 0Æ362

Female 89 29Æ5 11 36Æ7 78 28Æ7Ethnicity

White 125 41Æ4 5 16Æ7 120 44Æ1 8Æ39 0Æ004

African American 177 58Æ6 25 83Æ3 152 55Æ9Age (in years)

20–30 28 6Æ0 1 3Æ3 17 6Æ2 0Æ47 0Æ789

31–54 261 86Æ4 27 90Æ0 234 86Æ055 and up 23 7Æ6 2 6Æ7 21 7Æ7

Educational level

‡ GED or High School Graduate 257 85Æ1 19 63Æ3 238 87Æ5 <0Æ01 0Æ002

<Did Not Graduate High School or

Complete GED

45 14Æ9 11 36Æ7 34 12Æ5

Employment status

Yes 50 16Æ6 9 30Æ0 41 15Æ1 0Æ07 0Æ040

No 252 83Æ4 21 70Æ0 231 84Æ9Marital status

Never married 165 54Æ6 17 56Æ7 148 54Æ4 0Æ43 0Æ805

Married/Living with 64 21Æ2 5 16Æ7 59 21Æ7Divorced/Separated/Widowed 73 24Æ2 8 26Æ7 65 23Æ9

Income

<$13,000 216 71Æ5 27 90Æ0 189 30Æ5 5Æ58 0Æ018

‡ $13,000 86 28Æ5 3 10Æ0 83 69Æ5Health insurance

Yes 279 92Æ4 30 100 249 91Æ5 0Æ15 0Æ082

No 23 7Æ6 0 0Æ0 23 8Æ5English as primary language

Yes 301 99Æ7 30 100 271 99Æ6 1Æ00 0Æ901

No 1 0Æ3 0 0Æ0 1 0Æ4Recruitment site

One 182 60Æ3 20 66Æ7 162 59Æ6 0Æ57 0Æ450

Two 120 39Æ7 10 33Æ3 110 40Æ4



With this approach, if the 95% CI of a regression coefficient

does not include 0, this is equivalent to P < 0Æ05. (Shrout &

Bolger 2002). The unstandardized regression coefficient and

95% CI are reported in the results. Mediation was also

analysed through bootstrapping, as it has been shown that

bootstrapping estimates the significance of mediation effect

accurately (Shrout & Bolger 2002). To evaluate the final

model, Cohen’s (1988) effect size values for regression was

used, which specifies an R2 of 0Æ02 to be small and 0Æ13 to be

medium.

Results

Participants

The sample comprised 302 participants. Primarily men

(70Æ5%) and African American (58Æ6%), the sample had a

mean age of 43Æ9 years (SDSD 7Æ94) and an average of 13Æ0 years

of education (SDSD 2Æ70). Over 70% of the sample (n = 216)

reported household incomes of less than $13,000 per year.

Table 1 provides additional socio-demographic information

about the participants.

Health literacy

Overall, 9Æ9% (n = 30) of the participants were classified as

having inadequate/marginal functional health literacy (95%

CI = 7Æ05%, 13Æ83%). Total scores on the S-TOFHLA

ranged from 7–100 and, as expected, were heavily negatively

skewed, with a mean score of 90Æ09 (SDSD = 12Æ84, 95%

CI = 88Æ63, 91Æ54), median of 94 and mode of 98. A total of

53 participants (17Æ5%) scored 100 and 68Æ9% scored 90 or

above. Table 1 displays the difference in selected character-

istics between the two functional health literacy levels,

inadequate/marginal (£75) and adequate (>75).

HIV medication adherence, functional health literacy and

medication-taking self-efficacy

The mean adherence based on EEM for the sample was

67Æ71% (SDSD 32Æ91) for the average per cent of days with the

correct number of doses taken (95% CI = 63Æ98, 71Æ44).

There was no important difference in adherence levels

between patients having the inadequate/marginal and ade-

quate functional health literacy (U = 3845Æ50, Z = �0Æ521,

P = 0Æ602). Over three fourths of this sample (78Æ1%) had

adherence levels less than 95% and about half of the sample

(52%) had adherence levels less than 85%. In contrast to the

functional health literacy scores, adherence levels in the

sample were highly variable.

The mean self-efficacy beliefs score was 139Æ54 (SDSD 29Æ48),

with scores ranging from 17–170, suggesting a moderately

high level of self-efficacy beliefs. Self-efficacy belief scores did

not differ between inadequate/marginal and adequate func-

tional health literacy levels (U = �3997Æ00, Z = �0Æ183,

P = 0Æ855).

Stepwise multiple linear regression with the continuous

measure of medication adherence level as the outcome and

those variables that met selection criteria (self-efficacy beliefs,

health literacy, race, gender, age, education, employment

status, viral load and number of medications), showed

medication adherence to be significantly related to race,

self-efficacy beliefs, viral load and number of medications,

R2 = 0Æ089 (95% CI = 0Æ026, 0Æ169). African Americans had

significantly lower medication adherence than Whites,

b = �8Æ23 (95% CI = �15Æ25, �0Æ57). Greater medication

adherence was associated with higher self-efficacy beliefs,

b = 0Æ21 (95% CI = 0Æ08, 0Æ35). The participants with a

detectable viral load had significantly lower medication

adherence than the participants with an undetectable viral

load, b = �8Æ34 (95% CI = �15Æ93, �0Æ63). The participants

taking 2–3 medications had significantly higher medication

adherence than the participants only taking 1 medication,

b = 22Æ01 (95% CI = 2Æ43, 42Æ40). There was no important

difference in medication adherence between participants

taking 1 medication and those taking 4–5 medications,

b = 17Æ05 (95% CI = �3Æ86, 39Æ62). These results led to the

decision to reject both hypotheses; functional health literacy

did not have any important effect on medication-taking self-

efficacy; and functional health literacy did not have an

indirect, positive effect on HIV medication adherence,

mediated by medication-taking self-efficacy.

Discussion

The findings from this study indicate that there is no

statistically significant association between HIV medication

adherence and functional health literacy, as measured using

the S-TOFHLA. This is one of only a few published

investigations to examine functional health literacy and

medication adherence using electronic monitoring in people

living with HIV/AIDS.

These results are contrary to both our original hypotheses.

Functional health literacy was not related to medication-

taking self-efficacy. The non-significant correlation between

functional health literacy and medication adherence leads to

the rejection of our second hypothesis; medication-taking

self-efficacy did not mediate the association between func-

tional health literacy and HIV medication adherence. The

results do support one of the primary tenets in Bandura’s

A.M. Colbert et al.


theory; specifically, the critical role of self-efficacy in

projecting expected behaviour.

Our results support the work of Golin et al. (2002), Wolf

et al. (2004) and Paasche-Orlow et al. (2006), which all

reported no important correlationship between HIV medica-

tion adherence and functional health literacy. However, our

findings contradict separate research studies that did find an

important association. This discrepancy may be attributable

to the various methods for assessing functional health literacy

and adherence. Several of the studies measured adherence

using self-report which has potential problems with memory

and recall bias (Turner 2002). However, Golin et al. (2002),

the study with the most comprehensive assessment of

adherence, reported a mean adherence rate similar to ours

at 71Æ3%.

These findings specific to health literacy rates were quite

different than expected; based on previously published work

in this area, we anticipated that 18–20% of this sample

would have lower functional health literacy. Also of note is

that what is considered the definition for ‘higher’ and ‘lower’

health literacy is also highly variable across studies. For

example, Kalichman et al. (1999) used an amended version

of the S-TOFHLA that included an HIV-specific reading

comprehension section along with two of the standard

reading sections and the numeracy items. The authors

considered those with greater than 85% of the items as

correct to have higher functional health literacy and those

with 85% or less to have lower functional health literacy. In a

different study assessing HIV-knowledge, Kalichman and

Rompa (2000) used a cut-off of 80% as the distinction

between higher and lower functional health literacy. Golin

et al. (2002), conversely, used the S-TOFHLA reading

comprehension section as a continuous variable in model

testing. The most recent study, Paasche-Orlow et al. (2006)

and Wolf et al. (2007) both used the REALM, with grade

level cut-off points (less than sixth grade as inadequate,

seventh–eighth grade as marginal and ninth grade and higher

as adequate). Studies using the S-TOFHLA in other popula-

tions have used cut-off points varying from 67–75% for

inadequate/marginal. Most recently, Osborn et al. (2010)

introduced an HIV-specific test of health literacy called the

Brief Estimate of Health Knowledge and Action (BEHKA)

and found that when using this instrument to measure health

literacy, lower scores in health literacy were associated with

poorer adherence. To move research in health literacy and

medication adherence forwards, researchers will need to

come to a consensus about measurement.

Our results contradict the work of Wolf et al. (2007), who

found a statistically significant association between func-

tional health literacy and medication adherence that was

mediated by self-efficacy. Our findings may be the result of

differences in the measurement strategy or the limited

variability of functional health literacy in our sample. Wolf

et al. used a 4-day recall self-report to measure adherence and

dichotomized results as 100% or less than 100%; they also

used the REALM to measure functional health literacy. Our

results do support, however, the broad body of research that

has found self-efficacy to be associated with adherence.

Adherence, in contrast to functional health literacy, was

quite variable in the sample. This finding supports the reports

of sub-optimal adherence to HIV medication, such as Mills

et al. (2006) meta-analysis that showed average HIV medi-

cation adherence to be approximately 55%. Although there

may be variation in the adherence levels required for viral

suppression, Bangsberg (2006) noted that the probability of

viral suppression, reduced disease progression and reduced

mortality are increased with greater adherence levels, thereby

supporting continued efforts to maximize adherence in

people living with HIV/AIDS.

No matter what the reason for the less than optimal

adherence (barring, perhaps, personal choice), poorer adher-

ence alone suggests that patients with HIV have at least some

degree of difficulty with managing their health. Although the

S-TOFHLA may be able to measure part of the functional

health literacy construct – specifically reading comprehension

– it may not be able to measure all of the components

adequately. This is consistent with continued calls from

researchers for different and more comprehensive ways to

measure functional health literacy, including tools that are

disease specific, such as the newly developed BEHKA

(Osborn et al. 2010).

Limitations

Several limitations to this study must be noted. First, the

relatively small number of people exhibiting lower health

literacy limits the extent of the examination between the

associations (potentially due to factors such as the high

educational level of the sample or a selection bias). Although

EEM is considered reliable for measuring adherence, EEM is

not infallible. Turner and Hecht (2001) point out that EEM

assessment does not demonstrate definitively that pills were

actually taken by the participant. In addition, participants

may refuse to participate in studies using EEM because they

may need to discontinue use of medication reminder systems,

resulting in a selection bias (Turner & Hecht 2001).

However, despite these limitations, EEM assessment can

provide valuable insight into the individual’s capacity to

create and maintain a consistent medication-taking behav-

iour. The parent study attempted to manage this weakness by



asking participants to complete a daily medication-taking

journal, as described in the methods section.

Timing of the study and the rapid changes in medication

regimens for the treatment of HIV/AIDS may also be a

limitation, since the data collection began in 2004 and

regimens have been simplified over the years to allow for

fewer pills in a day. To address this, we examined the

association between both functional health literacy and

medication adherence with number of medications. The

number of HIV/AIDS medications that participants were

prescribed ranged from 1–5; this is similar to what is seen in

clinical practice today.

Finally, the study may also be limited because it is a

secondary data analysis; therefore the methodology and

measurement tools were selected to address other primary

research questions. However, the instruments and method-

ology addressed gaps in the literature and were appropriate

to the framework and the research question.

Conclusions

These findings have several important clinical implications

for nurses. First, adherence to medication for people living

with HIV continues to be an issue that warrants on-going

examination, with an understanding that there is no single

solution to this multi-factorial problem. The lack of an

important relationship between health literacy and medica-

tion adherence reinforces the idea that just because a patient

is able to easily read and understand a prescription does not

necessarily mean the patient is taking the medication as

prescribed. The results also suggest that African American

patients may be at higher risk for lower adherence rates.

Clinicians working with people living with HIV need to

assess adherence regularly with their patients; self-efficacy

may be another avenue to explore during the standard clinic

visit. Nurses need to ask patients about their self-confidence

in their ability to take their medications in their normal

schedule and when that schedule is disrupted; responses to

these questions may provide insight into individual medica-

tion taking behaviours.

These results identify several areas for additional

research. For example, researchers could design a study

to address specifically some of the limitations that may

have served as a deterrent to those with limited functional

health literacy, such as reading demands on recruitment

and data collection materials. Also, additional research

specifically targeted to individuals with lower functional

health literacy may contribute to a better understanding of

medication adherence in that particular population. The

racial differences that were identified warrant additional

exploration into how race, health literacy and medication

adherence may be related, and identify some potential bias

in the measurement strategy. Findings from Osborn et al.

(2007), where health literacy mediated the association

between race and HIV medication adherence support this

line of inquiry (Osborn et al. 2007). Interventions to help

patients more effectively manage their medication taking

are also clearly needed and incorporating strategies specif-

ically designed to improve self-efficacy should be consid-

ered. Finally, these results highlight the need for expanded

attention to how the functional health literacy construct is

being defined and measured to understand the role of

health literacy in self-management for chronic conditions

more fully.

What is already known about this topic

• Adherence is a critical component of HIV/AIDS

management; however, rates of medication adherence

are suboptimal.

• Health literacy has recently emerged as a potential

variable linked to chronic disease management,

although results have been contradictory.

• Self-efficacy has been shown to be related to medication

adherence in multiple populations, including those with

HIV/AIDS.

What this paper adds

• Health literacy assessed by the Short Test of Functional

Health Literacy in Adults may not be related to

medication adherence assessed using electronic

monitoring for adherence in a population actively

engaged in care.

• The connection between self-efficacy and HIV

medication adherence is further supported.

• African Americans were shown to be both more likely

to have inadequate health literacy and lower medication

adherence.

Implications for practice and/or policy

• Continued attention to medication adherence in the

clinical setting is critical.

• Helping people increase their self-efficacy around

medication taking may improve their adherence.

• Standardizing the way researchers, clinicians and policy

makers define and measure health literacy needs to

occur to better understand the problem and to improve

patient outcomes.

A.M. Colbert et al.


Acknowledgements

The authors appreciate the contributions of the staff of the

Managing Medications Project at the University of Pittsburgh

School of Nursing, and the assistance of Dr. Kevin Kim. The

authors also wish to thank the study volunteers for their

participation.

Funding

This study was funded by National Institute for Nursing

Research (NINR) of the National Institute of Health (R01

NR04749 and 2R01 NR04749) and a Clinical & Transla-

tional Science Institute Fellowship (Colbert).

Conflict of interest

No conflict of interest has been declared by the authors.

Author contributions

All authors meet at least one of the following criteria

(recommended by the ICMJE: http://www.icmje.org/

ethical_1author.html) and have agreed on the final version:

• substantial contributions to conception and design,

acquisition of data, or analysis and interpretation of data;

• drafting the article or revising it critically for important

intellectual content.

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